Refrigerant compressor with built-in reverse cycle valving



March 5, 1968 J. H. HEIDORN 3,371,502

REFRIGERANT COMPRESSOR WITH BUILT-1N REVERSE CYCLE VALVING Filed Aug. 26, 1.966 I 2 Sheets-Sheet 1 IIO lgos O INVENTOR.

John H. Heia'om 2 Qg a His Afforney March 5, 1968 J- H. HEIDORN REFRIG ER ANT COMPRESSOR WITH BUILT-1N REVERSE CYCLE VALVING 2 Sheets-Sheet 2 Filed Aug. 26,1966" INVENTOR. John H. He/aorn BY his Attorney United States Patent O 3,371,502 REFRIGERANT COMPRESSOR WITH BUILT-IN REVERSE CYCLE VALVING John H. Heidorn, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Aug. 26, 1966, Ser. No. 575,409 5 Claims. (Cl. 62-234) ABSTRACT OF THE DISCLQSURE In the preferred form, a refrigerant system having a compressor, an evaporator coil, a condenser coil and means for connecting them in series refrigerant flow relationship, a two-way valve positioned by operating means driven off a compressor drive shaft ino first and second flow directing positions with respect to first and second director ports in the compressor body thereby to periodically reverse the flow of the refrigerant through the condenser and the evaporator.

This invention is directed-to refrigerant systems and more particularly to improved apparatus for controlling the flow of hot refrigerant gas from a compressor for periodically defrosting an evaporator in refrigerant flow relationship therewith.

In refrigerant systems including a compressor, condenser, evaporator, and means for connecting the compressor, condenser and evaporator in series refrigerant flow relationship many systems'have been proposed to utilize the relatively hot refrigerant discharged from the compressor as a thermal source for removing frost buildup from the evaporator. A typical system of this type includes valve means in the refrigerant system that are solenoid operated or the like and selectively energizable under the control of a separate timer during a normal refrigerating cycle of operation to direct the hot gas from the compressor through the condenser thence through suitable expansion means to the evaporator and thence back to the compressor. The valve means are operated by the timer following a predetermined refrigerating cycle to direct the hot gas from the compressor directly to the evaporator hence to the condenser cycle of operation. The evaporator thereby has frost build-up thereon removed. In order to eliminate a separate timer from such systems, it has also been proposed to utilize the compressor drive itself to periodically operate control means for by-passing expansion valve means between the compressor and evaporator during a defrost cycle of operation whereby the refrigerant in the condenser is used for defrosting. A system of this type is disclosed in United States reissued Patent 20,150, issued Oct. 27, 1936 to Stickney.

In the automatic defrost systems of the type disclosed that utilize the thermal energy of hot gas from the compressor in a refrigerant system to carry out a predetermined defrost action on an evaporator therein the means for automatically producing the defrost cycle of operation requires substantial modification to refrigerant systems of the type commonly found in household refrigerators and the like. In such arrangements, moreover, it is desirable to limit the number of operative parts in the system for reversing the direction of refrigerant flow through the evaporator and it is desirable to arrange the operative parts of such a system in a highl compact fashion for accommodation in space limitations that are present in refrigerant systems for domestic refrigerators and the like.

Accordingly, an object of the present invention is to provide an improved unitary refrigerant compressor and ice valving mechanism for reversing the direction of refrigerant flow through an evaporator whereby, periodically, hot gas is directed to the evaporator for removing frost build-up therefrom. Y

A still further object of the present invention is to provide an improved refrigerant compressor having a built-in reverse cycle valving mechanism therein that is operative in response to the drive of a refrigerant compressor to automatically direct hot gas'discharged from the compressor directly into an evaporator for removing frost build-up therefrom.

Still another object of the present invention is to provide an improved motor compressor assembly having a hermetically sealed shell and wherein the compressor has an inlet and an outlet therefrom through which refrigerant is directed to and from a condenser and an evaporator of an associated refrigerant system by the provision of valving means located internally of the hermetically sealed shell operative selectively to direct refrigerant from the outlet of the compressor either to the condenser or the evaporator and further including means located interiorly of the hermetically sealed shell directly responsive to a predetermined number of revolutions of the compressor drive to operatively position the valving means to direct hot gas from the compressor to the evaporator during a predetermined defrost cycle of operation.

Still another object of the present invention is to provide a motor driven refrigerant compressor including a hot gas outlet and an inlet and wherein valving means v are integrally formed in a cylinder head of the compressor for selectively directing gas from the outlet thereof directly to an evaporator of an associated refrigerant system and wherein the valving means is shifted to its defrosting position by means operated directly by the drive shaft of the compressor.

Yet another object of the present invention is to improve defrosting of a refrigerant system including a rotary compressor driven by electric motor means and wherein the rotary compressor and electric motor means are enclosed by a hermetically sealed outer casing by the provision of fluid directing ports integrally formed in a cylinder head of the compressor and an associated movable valving component also supported in the cylinder head of the compressor and operable into first and second positions with respect to the fluid directing ports of the compressor for selectively directing hot gas discharged from the compressor either to a condenser or an evaporator of an associated refrigerant system and wherein within the compressor is located means for operating the valving component including an operating shaft continuously directly connected to the drive shaft of the compressor and associated gear means for producing a predetermined speed reduction from the drive shaft of the compressor to the operating shaft and linkage means connected between the gear means and the valving component for periodically shifting it to a position for directing hot gas from the compressor directly to the evaporator during a predetermined defrost cycle of operation; and to provide such a system wherein the linkage means for operatively connecting the speed reducing means to the valve means includes defrost cycle cam means and refrigeration cycle cam means periodically operated into a synchronized position wherein an operating lever for the valving component is conditioned to be operated into a defrost position and wherein following the defrost cycle of operation, the operating lever is conditioned for movement of the valving component into its normal refrigerating cycle position.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shOWn.

In the drawings:

FIGURE 1 is a view in vertical section of a portion of a hermetically sealed motor driven refrigerant compressor assembly associated with a diagrammatically illustrated refrigerant system;

FIGURE 2 is an enlarged fragmentary view in vertical section of an integral defrost timing mechanism operated by the drive shaft of the illustrated motor compressor assembly for automatically producing predetermined defrost cycles of operation in the system illustrated in FIGURE 1;

FIGURE 3 is a view in top elevation of the compressor shown in FIGURE 1 including an integral reverse cycle valving component and associated operating means for the valving component;

FIGURE 4 is a view in bottom elevation of the compressor shown in FIGURE 1;

FIGURE 5 is a schematic showing of a gear train within the timing mechanism of FIGURE 2.

Referring now to FIGURE 1, a portion of a hermetically sealed motor driven refrigerant compressor is illustrated of the type more specifically set forth in United States Patent 3,016,183, issued Jan. 9, 1962 to Murphy et al.

As is more specifically disclosed in the aforementioned United States patent, the assembly 10 includes a sealed outer casing 12 that hermetically encloses an interiorly located compressor drive motor including a stator 14 and a rotor 16 operatively connected to one end of a drive shaft 18 having the opposite end thereof journaled in an upper cylinder head or end plate 20 for rotation relative thereto. The drive shaft 18 further includes an eccentric portion 22 directed through a roller or piston 24 that is operated thereby within a compressing chamber 26 formed in a cylinder block 28. The shaft 18 further includes a small diameter end portion 30 thereon directed through a bottom cylinder head or end plate 32 for rotatably guiding the shaft 18 with respect thereto. As is better seen in the Murphy et al. patent, the end plates 20, 32 are interconnected with cylinder block 28 by suitable fastening means such as bolts being directed therethrough and include suitable fluid flow passageways therein including a low pressure passageway 34 formed in the upper cylinder block 20 for directing refrigerant into the compression chamber 26 wherein it is acted upon by the rotor 24 for subsequent discharge through an outlet 36 best seen in FIGURE 4 that communicates with a conduit 38 for directing hot refrigerant gas from the compressor through a super heat coil 40 thence to be returned through a conduit 42 into the interior 44 of the outer casing 12. The compressor includes sliding vane means associated with the roller 24 and suitable valving means for controlling fluid flow through the suction port 34 and the discharge outlet 36 therein all of which are, as well as the operation of the compressor, more detailedly set forth in the Murphy et al. patent to which reference may be had for a better understanding of its operation. While a rotary compressor is illustrated, it should be clearly understood that the improved defrost control system of the present invention is equally suited for association with other types of refrigerant compressors, for example those including a reciprocating piston to accomplish a refrigerant compressing function.

In the illustrated arrangement, the upper end plate 20 includes a plurality of circumferentially located lugs 46 thereon which are resiliently supported by coil springs 48 located on a like plurality of support brackets 50 secured to the inner surface of the lower end of the outer casing 12.

In accordance with certain principles of the present invention, the compressor cylinder block 28 is modified in practicing the invention to include a pair of refrigerant fluid directing ports therein at 52 and 54. The fluid directing port 52 communicates through a fitting 58 located in an opening in the lower end plate 32. The fitting 58 in turn is in communication with a conduit 60 that connects the fluid directing port 52 with one end of a refrigerant condensing coil 62 having the opposite end thereof in communication with one end of an elongated capillary tube 64 serving as a refrigerant expansion means in the associated refrigerant system. The opposite end of the elongated capillary tube 64 is connected to one end of a refrigerant evaporator coil 66 having the opposite end thereof connected by a conduit 68 that is directed interiorly of the outer casing 12 where it connects to a fitting 70 directed through the lower end plate 32 to communicate the evaporator 66 directly with the fluid directing port 54 in the cylinder block 28. In the illustrated arrangement, between the fluid directing ports 52, 54 is located a passageway 72 that communicates with the low pressure side of the pumping chamber 26 of the compressor through an inlet check valve of the type shown in the Murphy et al. patent.

The representatively illustrated motor compressor unit is of a high side type namely one wherein the hermetically sealed interior 44 has high pressure refrigerant gas directed thereto from the compressor and the refrigerant gas initially discharged from the compressor through the conduit 38 is cooled by the super heat coil 40 and directed into the interior 44 for removing heat from the motor enclosed therein.

In accordance with certain principles of the present invention improved means are associated with the fluid directing ports 52, 54 in the pumping cylinder 28 of the illustrated assembly to direct the hot gas discharged from the compressor directly into the evaporator 66 following a predetermined period of compressor operation to remove frost build-up thereon. More specifically, in the illustrated arrangement, and as best seen in FIGURES 1 and 3, the upper end plate 20 on one side thereof is recessed at 74 to define a valve guiding slot in the cylinder head 20 in which is located a valving component 76 formed as a slider block having a lower surface 78 thereon slidably supported by the upper surface of the cylinder block 28. Valving component 76 more particularly includes a passageway 80 that has one end thereof in intersecting relationship with the lower surface 78 of the valving component 76 and the opposite end thereof in communication with the up-right snorkle tube 82 that has an inlet end 84 located at a point above the upper surface of the upper end plate 20 as best in FIGURE 1. The valving component 76 further includes a cross-over passageway 86 that is formed in the lower face 78 thereof as seen in FIGURE 1.

The valving component 76 during a normal refrigeration cycle of operation is located in the position shown in FIGURE 1 wherein gas returned from the super heat coil 40 is directed through the snorkle 82 thence through the passageway 80 and through the fluid directing port 52 into the conduit 60 thence through the condenser 62 from whence the refrigerant is directed through capillary tube 64, an evaporator 66, and conduit 68 to be returned through when the director port 54 which is communicated by the cross-over passageway 86 in the valving component 76 to communicate the director port 54 with the low pressure communicating port 72 in the cylinder block 28 from whence refrigerant is directed into the low pressure side of the compressing chamber 26.'

In accordance with certain principles of the present invention, the valving component 76 is shiftable with respect to the directing ports 52, 54 whereby the refrigerant discharged by the compressor is passed from the interior 44 of the outer casing 12 directly into the evaporator 66 for increasing the temperature thereof to remove frost build-up therefrom during a predetermined defrost cycle of operation. More particularly, in the illustrated arrangement to accomplish this purpose, the small diameter end 30 of the drive shaft 18 is connected to a splined input shaft 88 of a speed reducing mechanism 90 that is responsive to the number of revolutions of the shaft 18 to periodically, in response to the drive of the compressor, cause operating lever 132 on the top of the compressor to produce a shifting movement of the valving component 76 to be discussed.

The speed reducing mechanism 90 includes a plurality of speed reducing gear and pinion units 92, 94, 9'6, 98, 100, and 102 inter-related through a gear train 115 in FIGURE 5 and supported on a gear plate 103 that is secured to the lower cylinder head 32 in spaced relationship therewith as established by a spacer 105 having suitable fastening means directed therethrough and secured to the end plate 32 as for example a screw 107.

The gear and pinion unit 102 has the pinion thereof meshed with a gear 104 secured to rotatable cross-over shaft 106 directed through the lower end plate 32, the compressor cylinder 28 and the upper end plate 20 as best seen in FIGURE 2. The shaft 106 in the illustrated arrangement, revolves at a predetermined lesser number of revolutions than does the drive shaft 18 so as to establish a predetermined timed relationship there'between. The shaft 106 further includes a plurality of teeth on the outer periphery thereof and at the upper end thereof is in driving engagement with a first output gear 108 having a pinion 110 thereon that in turn is in driving engagement with a second output gear 112 and also in driving engagement with a cam drive gear 114 that is secured to a tubular, depending shaft 116 on a defrost cam 118 for causing counterclockwise rotation thereof as seen in FIG- URE 5. The second output gear 112 has a pinion 120 thereon that meshes with a second cam gear 112 that is directly secured to a refrigeration cycle cam 124 that is driven thereby in a clockwise direction as seen in FIG- URE 5.

The defrost cam 118 has a peripheral slot 126 therein and the refrigeration cycle cam 124 has a peripheral slot 128 thereon and the cams 1'18, 124, are driven relative to one another whereby the slots 126, 128 are periodically located in aligned relationship with one another.

The upper end of the cross-over shaft 106 is directed through the tubular shaft 116 that depends from the defrost cam 118 as best seen in FIGURE 2 and it is secured to an operating cam 130 that is driven as shown in FIG- URE 5 in a counter-clockwise direction at a r.p.m. equal to that of the cross-over shaft 106. The valving component 76 has one end of an operating lever 132 secured thereto by a pin 134 and the operating lever 132 bends outwardly about the journal hub of the upper end plate 20 as best seen in FIGURE 3 so as to be freely shiftable with respect thereto and includes a distal portion 136 having a lost motion slot 138 formed therein through which is directed a cam follower 140 that depends from the end of one arm 142 of a lever retaining spring 144. The lever retaining spring 144 includes a snap ring portion 146 that is seated in a groove 148 in the journal hub of the upper end plate 20 whereby a second arm 149 of the spring 144 is located in overlying engaging relationship with the end of the operating lever 132 that is secured to the valving component 76 thereby to spring bias the valving component surface 78 into sealing sliding engagement with the upper surface of the cylinder block. 28 at the portion thereof exposed to the recess 74 in the upper end plate 20. The spring144 further includes a third arm portion 150 thereon that is directed radially outwardly of the snap ring 146 to overlie the operating cam 130 to spring bias it in a retained relationship on the upper end of shaft 106. This feature is best illustrated in FIGURE 2.

The operating lever 132 further includes a notched surface 152 in the distal end 136 thereof and an extended surface 154 thereon that runs through a predetermined radius from the notched portion 152 to the point where the operating lever 132 clears the journal hub of the upper end plate 20. a

By virtue of the above illustrated assemblage of parts,

assuming that the refrigerant compressor and associated refrigerant system is initially operative during a normal refrigerant cycle of operation, the operating arm 132 is shifted to the position shown in FIGURES 1 and 3 to produce the normal refrigerant cycle of operation discussed above. The cross-over shaft 106 will drive the pinions 110, to produce a relative rotation between the defrost cam 118 and the normal refrigeration cycle cam 124 whereby eventually the slots 126, 128 in the outer periphery thereof will be moved synchronously into alignment with one another at the point of the cam follower 140. When this occurs, the cam follower will move radially inwardly of the cams so as to locate the operating lever notched portion 152 in alignment with the end of operating cam which will rotate at its predetermined accelerated rpm. in a counter-clockwise direction to engage thenotched portion 152 and cause the operating lever 132 to be shifted to the left as viewed in FIG- URE 1 whereby the valving component 76 will have the cross-over passageway 86 therein aligned to inter-communicate the director port 52 with the low pressure passageway 72. The valving component 76 is shifted far enough to the left whereby the other fluid directing port 54 will be in direct communication with the interior 44 of the motor driven compressor assembly. When this occurs, hot gas being discharged from the discharge port 36 will pass through the conduit 38, super heat coil 40 thence through the conduit 42 and back again to the interior 44 of the compressor as was previously discussed and will thence be passed into the exposed fluid directing port 54, the fluid fitting 70 and thence through the fluid conduit 68 directly into the evaporator coil 66 where the relatively hot gases will serve to remove frost build-up thereon. Refrigerant will by-pass the capillary tube 64 through conduit 67 and check valve 69 thence pass through the condenser coil 62, conduit 60, fluid fitting 58 thence through the fluid directing port 52 and through the crossover port 86 into the low pressure passageway 72 for passage into the compressing chamber 26 of the compressor whereby the refrigerant cycle is completed.

The defrost cam 118 will continue to rotate faster than the normal refrigeration cycle cam 124 whereby the slot 126 therein will be moved out of alignment with the slot 128 in the refrigeration cycle cam 124 thereby causing the cam follower to be shifted radially outwardly of the outer periphery of the cams 118, 124 and concurrent rotation of the cam 130 will cause the end thereof to engage the surface 154 on the shifted operating lever 132 following a predetermined period of time representing the defrost cycle of operation of the above described mechanism wherein the operating lever 132 will be shifted back to its normal refrigeration cycle of operation position. Upon further rotation of the operating cam 130, the notched portion 152 of the operating lever will be located radially outwardly of the end of the rotating operating cam 130 for a substantial period of time until the slots 126 and 128 are again aligned with the cam follower 140 so as to align the operating lever 132 in a position so that it will be acted upon by the operating cam 130. The period that is required to produce alignment of the slots 126, 128 and the cam follower 140 constitutes the normal refrigeration cycle in the illustrated system.

By virtue of the illustrated arrangement, automatic defrosting of an evaporator coil is accomplished by utilizing the hot gas discharged from a refrigerant compressor and moreover, the mechanism enables this function to occur without the necessity of a separate timer mechanism or without requiring any substantial modification of conventional refrigerant compressors of relatively compact configuration such as that illustrated in the representatively shown embodiment of the invention. Furthermore, the operative parts of the mechanism for obtaining a cyclical movement of the built-in reverse cycle valving component are located in an oil sump 156 of the motor compressor assembly to be continually lubricated to reduce frictional wear. Furthermore, the hermetically sealed shell 12 protects the operative components of the valve operating system against dirt, dust, and the like in the environment surrounding the outer casing 12.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a gas defrosted refrigerant system, the combination of a compressor having an inlet and an outlet, drive means including a shaft for driving said compressor, a compressor housing having first and second flow directing ports, a condenser coil, an evaporator coil connected to said condenser coil in series refrigerant flow relationship, means to connect said first flow directing port to said condenser coil, means to connect said second fiow directing port to said evaporator coil, a valve having first and second passageways, said valve being movable with respect to said first and second flow directing ports into first and second flow controlling positions, said first position of said valve aligning said first valve passageway with said first flow directing port to define a refrigerant flow path from said compressor outlet to said condenser coil, said second flow directing port being in refrigerant flow communication between said evaporator coil and said compressor inlet when said valve is in said first position, said second position of said valve communicating said compressor outlet and said second flow directing port with said evaporator coil to provide reverse refrigerant flow therethrough, said second valve passageway being aligned with said first fiow directing port to provide refrigerant flow communication between said condenser coil and said compressor inlet when said valve is in said second position, and valve control means for moving said valve between said first and second positions and driven by said compressor drive shaft.

2. In combination with claim 1, a sealed outer casing hermetically enclosing said compressor, said compressor drive means, said valve, and said valve control means.

3. In a gas defrosted refrigerant system, the combination of a compressor having an inlet and an outlet, drive means including a shaft for driving said compressor, a compressor housing having first and second fiow directing ports, a condenser coil, an evaporator coil connected to said condenser coil in series refrigerant fiow relationship, means to connect said first flow directing port to said condenser coil, means to connect said second flow directing port to said evaporator coil, a valve having first and second passageways, said valve being movable with respect to said first and second fiow directing ports into first and second flow controlling positions, said first position of said valve aligning said first valve passageway with said first flow directing port to define a refrigerant flow path from said compressor outlet to said condenser, said second flow directing port being in refrigerant flow communication between said evaporator coil and said compressor inlet when said valve is in said first position, said second position of said valve communicating said compressor outlet and said second flow directing port with said evaporator coil to provide reverse refrigerant flow, said second valve passageway being aligned with said first flow directing port to provide refrigerant flow communication between said condenser coil and said compressor inlet when said valve is in said second position, and valve control means for moving said valve between said first and second positions and driven by said compressor drive shaft, a sealed outer casing hermetically enclosing said compressor, said compressor drive means, said valve, and said valve control means, a super heat coil in fluid flow connection with said compressor outlet and having an outlet in said sealed outer casing, said first valve passageway of said valve extending above said valve whereby refrigerant flow communication is provided from said compressor outlet, through said super heat coil, through said sealed outer casing, and into said first valve passageway.

4. In a gas defrosted refrigerant system, the combination of a compressor having an inlet and an outlet, :1 drive means including a shaft for driving said compressor, a compressor housing having first and second fiow directing ports, a condenser coil, an evaporator coil connected to said condenser coil in series refrigerant flow relationship, means to connect said first flow directing port to said condenser coil, means to connect said second flow directing port to said evaporator coil, a valve having first and second passageways, said valve being movable with respect to said first and second flow directing ports into first and second fiow controlling positions, said first position of said valve aligning said first valve passageway with said first flow directing port to define a refrigerant flow path from said compressor outlet to said condenser coil, said second flow directing port being in refrigerant flow communication between said evaporator coil and said compressor inlet when said valve is in said first position, said second position of said valve communicating said compressor outlet and said second flow directing port with said evaporator to provide reverse refrigerant flow, said second valve passageway being aligned with said first fiow directing port to provide refrigerant flow communication between said condenser coil and said compressor inlet when said valve is in said second position, and valve control means for moving said valve between said first and second positions and driven by said compressor drive shaft, said valve control means comprising gear means driven by said compressor drive shaft and having a first, second and third output, each of said first and second outputs including a cam having a recessed peripheral surface, a cam follower positioned so as to move to an indented position when said cam follower is aligned with said cam recessed peripheral surface of both said first and second outputs, said third output including another cam, a valve operating arm engaging said cam follower so as to be directed into the path of said third output cam when said cam follower is in said indented position whereby said valve operating arm moves said valve into said second position.

5. In a gas defrosted refrigerant system, the combination of a compressor having an inlet and an outlet, compressor drive means including a drive shaft, a condenser, an evaporator connected to said condenser in series refrigerant flow relationship, a valve having a first position and a second position to selectively control refrigerant flow from said compressor outlet, said valve in said first position directing refrigerant flow to said condenser and then to said evaporator, said valve in said second position directing refrigerant flow to said evaporator and then to said condenser, valve control means for moving said valve between said first and second positions and driven by said compressor drive shaft, said valve control means comprising gear means driven by said compressor drive shaft and having a first, second and third output, each of said first and second outputs including a cam having a recessed peripheral surface, a cam follower positioned so as to move to an indented position when said cam follower is aligned with said cam recessed peripheral surface of both said first and second outputs, said third output including another cam, a valve operating ram engaging said cam follower so as to be directed into the path of said third output cam when said cam follower is in said indented position whereby said valve operating arm moves said valve into said second position.

References Cited UNITED STATES PATENTS 1,791,850 2/1931 Stickney 62-234 2,166,602 7/1939 McGrath 62154 2,617,900 11/1952 Morrison 62-234 WILLIAM J. WYE, Primary Examiner. 

